4.3 Run an assembly program

In the file sample.S there are instructions on how to assemble the code using the FSF gcc compiler.

Follow the instructions.

/* Louis Taber   11/1/97  PCC                         */
/*                                                    */
/*  Sample program for assembly language              */
/*  subroutines on Linux.  These are compiled         */
/*  and linked as follows:                            */
/*                                                    */
/*  If compiled/assembled together.                   */
/*       gcc -nostdlib -o sample sbr.S sample.S       */
/*                                                    */
/*  If comples as seperate modules.                   */
/*       gcc -nostdlib -o sample sbr.o sample.S       */
/*                                                    */
/*  To assemble the library to object                 */
/*       gcc -c sbr.S                                 */
/*  this will create the object file for the library  */


#define FILE_STDIN    $0     /* file handle for stdin      */
#define FILE_STDOUT   $1     /* file handle for stdout     */
#define FILE_ERROR    $1     /* file handle for stderror   */

#define LINUX_SYS     $0x80  /* interrupt for system calls */

                             /* Values for system calls    */
                             /* defined in unistd.h        */
#define LINUX_EXIT   $1
#define LINUX_READ   $3
#define LINUX_WRITE  $4
 
        .file           "sample.S"
        .version        "01.01"
        .data
head:   .string         "Sample gcc/linux assembly"
                        " language program\n\n"
request:
        .string         "Please input a hexadecimal number: "
eop:    .string         "\nThe program is done.\n"
hex:    .string         "       Hexadecimal: "
dec:    .string         "       Decimal:  "
        .text
        .align 16
        .globl          _start
        .type           _start,@function

_start:  xorl            %ebp,%ebp        /* clear bp */
        andl            $0xfffffff8,%esi  /* align stack to */
                                          /* 8 byte boundry */
	
        movl    $head,%esi
        call    pstring

        movl    $request,%esi      /* print out program heading */
        call    pstring
        call    getline            /* get input string */
        call    char2num           /* convert to number */

        movl    $dec,%esi
        call    pstring
        call    pnumd              /* print in decimal */
        call    new_line           /* keep output neat */

        movl    $hex,%esi
        call    pstring
        call    pnumnl             /* print in hex */
        call    new_line           /* keep output neat */

        movl    $12,%ecx           /* load loop counter */
        movl    $1,%eax            /* starting point */
        movl    $2,%ebx            /* for multiply */
loopa:  call    pnumd              /* print decimal number */
        movb    $' ',%dl           /* get a space */
        call    putchar            /* print the space */
        call    pnumnl             /* print number in hex */
        mull    %ebx               /* factorial series */
        inc     %ebx	
        loopl   loopa


        movl    $eop,%esi
        call    pstring

        movl    LINUX_EXIT,%eax    /* exit code */
        int     LINUX_SYS          /* call OS */
        hlt                        /* exit should not return */

        .align	16

        .comm	d,1,1
	.ident	"GCC: (GNU) 2.7.2.1"

The subroutines can be found at: ftp://phred.dcccd.edu/pub/ltaber/sbr.S.

Run the program, it puts out a factorial series.

sample 

sample | tee temp
lpr temp

Your-Name
Lab 4.3: assembly
TABER CSC135